A study of the effect of particulate deposit upon fibrous filter efficiency

The aim of this work is to develop numerical methods to model the effects that particle deposit collected by fibrous filters has upon the flow field within the filter and hence upon further deposition. A single fibre model has been developed with the deposit modelled as a porous layer on the fibre surface. Using mathematical techniques the flow field outside and within the porous layer are determined. Once the flow field for a particular deposit has been obtained the equations of motion of the particles are solved and the feedback effects of the deposit upon further deposition investigated. The mechanisms of interception and diffusion are considered. It is found that for the smaller particles the porosity of the deposit has an insignificant effect upon the flow field. However the porosity becomes increasingly important as the relative size of the particle to the fibre increases.